The wise guy

When he turns 70 next week, Martin Scorsese can be confident of his place in the pantheon of cinema. He is the greatest American director now working, and the most influential director of the past 40 years. If you asked David Fincher, Clint Eastwood, Terrence Malick or Steven Spielberg, they would probably agree. His influence has been profound; his output extraordinary across a huge range of styles. A film magazine poll a few years back ranked him second of all time, behind Hitchcock. In 20 years, I suspect it might go the other way.

Scorsese reinvented modern American cinema in his own image, rather than shaping himself to fit. That has cost him throughout his 50-year career. He has been an outsider from the start, pursuing the personal goals of an ''artist'' - a word that makes the average studio executive shudder. Until his relatively recent ascent into Hollywood's highest church, when he finally won the Oscar for best director with The Departed (2006) on his sixth nomination, he was admired, respected, but not loved. His films were too tough for Hollywood, and most audiences. He has always refused to flatter the American public. Right from the start, as a film student in the 1960s in New York, he made audiences feel uncomfortable.

In Mean Streets (1973) and Taxi Driver (1976), his technical boldness and profound taste for experimentation caught up with his sanguine world view. Both films were infested with Catholic guilt and sexual longing, energised by a restless camera that never stopped prowling and was unafraid of violence; shockingly real violence. While Francis Ford Coppola was making an opera with The Godfather, and Spielberg was playing with trucks and sharks in Duel and Jaws, Scorsese went into the darkness of New York City, looking for his own reflection.

That's Travis Bickle (Robert De Niro) in Taxi Driver, a Vietnam vet with a dangerous desire to clean up the streets. It's also Martin Scorsese, the altar boy who grew up hanging out with wise guys in Little Italy in the 1950s, looking at things no child should see. The effect of his childhood is crucial to an understanding of his artistic ambitions. His films are suspended between heaven and hell and he knows about both - even if the Catholic Church wanted to excommunicate him for The Last Temptation of Christ (1988).

In a sense, he was lucky in his childhood misfortunes. His first seven years were spent in relative comfort in Queens, New York. His father and mother, both children of Sicilian migrants, had made it as far as Flushing when Scorsese was born. Then his father hit hard times, so they had to move back to Elizabeth Street, near the centre of Italian working class life in Manhattan. This is where life hit him hard.

It was a brutal neighbourhood, with ''wise guys'' attending the ''social club'' across the street, publicly executed murders and beatings, and babies flung off roofs near where the young Scorsese was playing. He talks about stepping over the bodies of derelicts on his way to school.

Scorsese was asthmatic, his other ''lucky'' misfortune. He wasn't tough enough to be one of the thugs, although some were his friends. He needed constant supervision, so his father and mother often took him to movies. He saw everything, sometimes several times. His boyish tastes were for westerns and fantasy, the bigger and brighter and more colourful the better. This combination of violence on the streets, a neighbourhood of tough guys and a little boy's gasping reaction to high onscreen drama stoked an active imagination. He was already interested in art, drawing the characters from movies and comics and books. Add the family's tribal form of Catholicism, to which he was hugely attracted, and you have a young man with a lot on his mind.

It's a mistake to think that movies alone made him. His film knowledge is as deep as an ocean, but so is his knowledge of life. He did not become the master simply by being a film buff. His works tackle big issues and hard questions. They are, above all, personal.

Studying at New York University at a time when American cinema was in crisis, Scorsese evolved a credo: ''Personal cinema is the only kind worth making''. He was an apostle of John Cassavetes, who proved that it could be done cheap and good and tough with Shadows in 1959.

Everyone at that time agreed on the need to make personal movies, but few of them stuck to it as Scorsese did. If films are not films to Scorsese, his subjects are also not simply his subjects. It may be the greatest boxing movie made, but Raging Bull (1980) is not about boxing. The sport bores him. It is about a man who survives against the odds of his own nature. Scorsese had just come through a serious cocaine addiction that nearly killed him. He and guitarist Robbie Robertson had partied too hard after The Last Waltz (1978), his stunning film about the last concert of the Band. Scorsese ended up in hospital; De Niro rescued him. Scorsese poured everything he knew into Raging Bull: all he had learnt about the American dream, the nature of men, the brutality of couples, the power of redemption, the price of the hatred of self.

He thought it might be his last film, so why not?

At the same time, he is not simply an auteur in a European sense. He has developed a new kind of American cinema, driven by deep emotional drives, characterised by kinetic energy and tempered with both humour and violence. No one had moved the camera the way he did, making it a voyeur in the action of the scene (take a look at The Age of Innocence to see how subtly he does it); no one had mounted violence as he did in Goodfellas (1990) and Casino (1995), in a way that was so disturbingly attractive and funny as well as shocking. No one had held a mirror to the darker side of the American psyche and said, ''Look what we have become'', like a crusading priest.

Now he has reached emeritus status and a certain bankability after the success of The Departed, Shutter Island and Hugo, he shows no sign of slowing down. As I write, he is reported to be working on The Wolf of Wall Street with Leonardo DiCaprio; Silence, about two Jesuit priests going to Japan in the 17th century; a long-awaited biopic of Sinatra (oh boy, oh boy!); and The Irishman, a film that will reunite him with De Niro and Joe Pesci, and sees him work for the first time with Al Pacino. Oh, and there's also a series on the history of rock music, his greatest love after movies.

Buon compleanno, Marty, and thanks for all the tracking shots, the wise guys in weird shirts, the crucifixions and killers, the sinners and the saved, the blood on De Niro's nose and Joe Pesci's knife, and the tear in Michelle Pfeiffer's eye. You were right all along: movies are about life, not the escape from it.

twitter.com/ptbyrnes

''Films are not films to me. They are life … especially if truthful. A film that reaches a certain kind of truth, you learn from it. It's like reading a certain philosophy, or trying to practise a certain philosophy.''